1. Field of the Invention
One embodiment of the present invention relates to a display device, a semiconductor device, and a light-emitting device.
Note that one embodiment of the present invention is not limited to the above technical field. One embodiment of the invention disclosed in this specification and the like relates to an object, a method, and a manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a display device, a semiconductor device, a light-emitting device, a power storage device, a storage device, an electronic device, a lighting device, an input device (e.g., a touch sensor), an output device, an input/output device (e.g., a touch panel), a driving method thereof, and a manufacturing method thereof.
2. Description of the Related Art
A variety of display devices ranging from large display devices such as television receivers to small display devices such as cellular phones are put on the market. As higher value added products, display devices capable of displaying stereoscopic images have been actively developed to provide more realistic images.
Physiological factors in recognition of objects as stereoscopic objects by humans are binocular parallax, convergence, focus slide, motion parallax, object size, spatial layout, contrast, shading, and the like.
For example, a display device that displays a stereoscopic image using binocular disparity is known. Such a display device is configured to display, on one screen, an image to be seen from the position of the left eye of a viewer (an image for left eye) and an image to be seen from the position of the right eye of the viewer (an image for right eye). The viewer sees the image for left eye with the left eye and the image for right eye with the right eye and is thus allowed to see a stereoscopic image.
As one example of display devices using eyeglasses, there is a display device which displays an image for left eye and an image for right eye alternately on a screen in synchronization with a shutter provided in eyeglasses, whereby the left eye of a viewer is allowed to see only the image for left eye and the right eye of the viewer is allowed to see only the image for right eye. Thus, the viewer can see a stereoscopic image.
Furthermore, in a display device using a parallax barrier which allows a viewer to see a stereoscopic image with naked eyes, a screen is divided into a plurality of regions for left eye and a plurality of regions for right eye (e.g., strip-like regions) arranged side by side. A parallax barrier is provided to overlap with the boundaries of the regions. On the divided screen, an image for left eye and an image for right eye are displayed at the same time. With the parallax barrier, the regions for displaying the image for right eye are hidden from the left eye of a viewer and the regions for displaying the image for left eye are hidden from the right eye of the viewer; consequently, the left eye is allowed to see only the image for left eye and the right eye is allowed to see only the image for right eye. Thus, the viewer can see a stereoscopic image.
Note that a display device including a switchable parallax barrier for achieving switching between a two-dimensional image display mode and a stereoscopic image display mode is known (Patent Document 1).
In addition, a light-emitting element using an electroluminescence (hereinafter also referred to as EL) phenomenon is also known. This light-emitting element is a self-luminous type; therefore, high contrast and high speed of response to an input signal are achieved. Furthermore, a display device to which this light-emitting element is applied and which consumes low power, is manufactured in a simple process, and is easily adapted to the increase in definition and the size of a substrate is known (Patent Document 2).